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Researcher: Hsin-I Chang

The Aerosol Radiative Effect on Surface LHF: using Off-Line Simulation of GEMTM via Land Information System (LIS)

Objective: Examine the aerosol radiative effect on the surface LHF via off-line GEMTM simulation. In general, LHF is greater over forestland owing to the vigorous transpiration and evaporation of water trapped within the leaf, while LHF is lesser over grassland owing to lack of soil moisture uptake, unless there is a strong stomatal resistance. This results in the spatially heterogeneous LHF that generates a mesoscale circulation between forestland and grassland (Pielke 2001).

Simulation method:

The off-line simulation will be implemented with the retrospective atmospheric forcing from the North American Land Surface Data Assimilation (NLDAS) and a number of MODIS land products in the Land Information System (LIS), which is a high performance land surface modeling and data assimilation system based on GSFC's LDAS ( Peters-Lidard et al. 2004).

The ecology model GEMTM will be used as a root model to compute effluence, uptake, and branching, which explicitly account for leaf-level processes, canopy microclimate soil abiotic processes, plant growth, and biomass production dynamics. The plant canopy is divided into shaded leaf and sunlit leaf sub-layers in a canopy microclimate submodel, and stomatal conductance and photosynthesis of shaded and sunlit leaves are simulated separately. The leaf photosynthesis submodel distinguishes the C3 and C4 pathway.

Text Box:        Fully coupled                     <GEMRAMS>  >

Both the point observation and satellite observations will be used to calibrate the off-line mode of the GEMTM in the LIS across the Southeastern part of United States (Matsui 2004).

Calibration of local LHF with point observations:

Once the canopy radiative transfer scheme is calibrated, sensitivity of the sunlit and shaded LAI-based stomatal conductance and associated LHF will be examined under clear, hazy, and cloudy conditions at the different ground observational sites through out the United States . Each of observational sites contains the carbon flux, soil, DDR and AODs data. Off-line GEMTM simulation will be implemented within the LIS platform.

Current task:

Set up the GEMRAMS model and have it run successfully at Purdue University cluster.

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